Here is what’s under the surface of Lake Baikal, the world’s largest freshwater lake by volume which contains about 22–23% of the world’s fresh surface water.
According to Wikipedia, with 23,615.39 km3 of fresh water Baikal contains more water than the North American Great Lakes combined. With a maximum depth of 1,642 m (5,387 ft), it is the world’s deepest lake, and is considered among the world’s clearest lakes. It is also believed to be the world’s oldest lake – at 25–30 million years. In terms of surface area, it is the seventh-largest lake in the world.